TITLE
Method for producing synthesis gas from fluidized bed gasification of high ash coals with adjustable H2/CO ratio in the gas composition.
FIELD OF INVETION
The present invention generally relates to fluidized bed coal gasification of high ash Indian coals to produce synthesis gas (syngas) for various applications like power generation, liquid fuels and chemicals production. More particularly the invention relates to producing syngas with the desired H2/CO ratio in syngas composition by varying operating temperature and fluidizing medium composition (oxygen and steam).
BACKGROUND OF THE INVENTION
Gasification is a process of converting carbonaceous fuels into combustible gases also called syngas through partial oxidation of the fuel. Gasification process is endothermic in nature and heat required for the conversion process is acquired from the partial combustion of the fuel. The amount of fuel left after partial combustion will be participated in gasification reactions which leads to combustible gases generation. The amount of fuel subjected to partial combustion depends on the desired gasification conditions like operating temperature, fuel & reactants throughput and bed weight. For a given conditions, one would prefer to subject more fuel into gasification reactions for a minimal partial combustion of fuel. Equivalence Ratio (ER) is a parameter defined as ratio of oxygen to carbon that is actually admitted into system to the stoichiometric ratio of oxygen to carbon required for full combustion of fuel. ER parameter is a characteristic of the amount of carbon subjected to partial combustion in order to maintain desired gasification conditions.

Fluidized bed gasification technology is the most suitable to gasify high ash Indian coals to produce syngas with air, oxygen, carbon dioxide and steam mixtures as reactants. Syngas is mixture of Carbon monoxide (CO), Hydrogen (H2), Methane (CH4), Carbondioxide (C02), water vapor (H20) and Nitrogen N2). Syngas is used for multiple applications like power generation, liquid fuels and chemicals production. Combination of these reactants are chosen as fluidizing medium depending on end application of syngas. For power generation application, syngas with maximum possible calorific value is required whereas for other applications it is desired to produce syngas with more H2/CO ratio. For example, H2/CO ratio of 2 is required to produce methanol and liquid fuels from syngas whereas H2/CO ratio of 1 is required for Di Methyl Ether (DME) and as high as possible for production of hydrogen fuel. If the required H2/CO ratio is not available in syngas then it has to be adjusted by passing through water gas shift reactor which adds additional unit to the plant. Generating syngas with suitable composition required by end application by varying parameters within gasifier is gaining more attention and demand.
In prior art, CN 1428403 A relates to the method of producing syngas with suitable H2/CO ratio required for liquid fuel production from co-gasification of coal and methane. This invention claims the method for preparing synthetic gas by using fluidized bed coal and methane-enriched fuel gas through co-gasification includes the following steps: breaking raw material coal and making its grain size be less than 8 mm, making the broken coal pass through drying system, raw coal bin and metering system, and feeding the coal into fluidized bed gasification furnace, making steam and oxygen gas pass through gas distribution plate, ash-removing ring pipe and central jet pipe and come into the gasification furnace, and feeding methane-enriched natural gas, coal layer gas or gas discharged from chemical fertilizer plant into concentration phase section reaction zone of fluidized bed gasification furnace from its lower or side portion gas inlet pipe to make co-gasification with coal at 950-1 lOOdeg.c to prepare synthetic gas. This invention further claims coal and methane-rich fuel gas co-gasification syngas composition of H2 / CO ratio of less than 1.5, typically about 1.3, fully in line with the needs of a variety of chemical

synthesis. In this process, coal and methane-rich fuel gas feed ratios of the process can be adjusted over a wide range, so that the process can be with coal as raw syngas can also be equipped with a certain amount of rich synthesis based on market prices and demand. Getting continuously supply of required methane for producing syngas with required H2/CO ratio through this method would be challenging task. The fluctuating and high costs of methane would raise the project sustainability issues over period of time.
Another prior inventionUS 20050150820 Al, relates toNovell integration of gasification, hydrocarbon synthesis unit, and refining processes to produce syngas with required H2/CO ratio and also pure hydrogen required for various refinery applications. This invention relates to integration of refinery hydroprocessing units, heavy hydrocarbons (pet coke, resides oil, etc) gasification units, and GTL plants through separation means that include membrane permeation, adsorption and absorption to effectively utilize H2 containing and syngas streams at reduced expenditures.Hydrogen-rich refinery purge is used to raise the H2/CO ratio ofsyngas. A hydrogen-enriched syngas is produced with an H2/CO ratio favorable for the production on synthetic hydrocarbons (greater than about 1.5 to about 2.0 or higher). Pure hydrogen is also produced in a PSA unit, to further raise the H2/CO ratio of the syngas and provide hydrogen feed for refinery hydrotreators and synthetic hydrocarbon units (such as methanol units). Additional purification units has to be set up to separate hydrogen from purge gases and integration issues has to be taken care in order to improve H2/CO ratio.
In another prior invention, WO 2007009984 Al relates to Preparation ofsyngas suitable for Fisher-Tropsch process by combining syngas generated through two different sources. One fuel source with low hydrogen to carbon ration and the other fuel source with high hydrogen to carbon ratio. The present invention discloses a process for the preparation of syngas from two sources with different hydrogen:carbon ratios, the first source having a low hydrogen : carbon ratio including any one or a combination of coal, brown coal, peat, bitumen and tar sands,

and the second source having a high hydrogen: carbon ratio including any one or a combination of natural gas, associated gas and coal bed methane. The sources are converted to syngas and then combined to provide syngas with an optimum hydrogen: carbon monoxide ratio for use in a Fischer-Tropsch process. The first source is converted into a first syngasstream with a low hydrogen: carbon monoxide ratio, and the second source is converted into a second syngas stream with a high hydrogen: carbon monoxideratio; the first and a part of the second syngas streams are combined into a combined syngas stream, the combined stream having an H2/CO-ratio of between 1.1 and 1.9, preferably between 1.3 and 1.7, while using the other part of the second syngas stream for hydrogen supply. This invention has a drawback of setting up two separate process lines to generate syngas stream lines from two different sources.
In another prior invention, US 20130005838 Al relates to method for adjusting hydrogen to carbon monoxide ratio in synthesis gas through water gas shift reaction (WGS). This invention claims a method for adjusting hydrogen to carbon monoxide ratio of syngascontaminated by sulfur impurities involving a water gas shift (WGS) reaction. In light of the presence of the sulfur impurities, the WGS can be implemented as a sour gas shift. WGS can provide good results by using a non-sulfided catalyst. Conditions can be employed which contribute to further enhanced CO-conversion in the reaction. The hydrocarbons or derivatives thereof obtainable from the method can further be refined and used for production of fuels or lubricants for combustion engines. WGS plays important role in achieving required syngas composition. Maintain ace of catalyst in WGS and conditioning syngas to meet the inlet requirements of WGS are the drawbacks of this invention
In another prior invention, US 9096802 relates to method of producing a hydrocarbon composition of suitable H2/CO ratio by mixing syngas generated from biomass gasification and hydrogen rich gas generated through catalytic reforming of hydrocarbon gas produced in the process of Fisher-Tropsch process. Method of producing a hydrocarbon composition in which a biomass raw-material is gasified to produce a raw syngas containing carbon monoxide, carbon

dioxide and hydrogen, the hydrogen-to-carbon monoxide ratio being about 0.5 to 1.7. A part of the impurities is removed to produce a clean syngas which is fed into a Fischer-Tropsch reactor where a significant part of the carbon monoxide and hydrogen is converted to a hydrocarbon composition containing C4-C90 hydrocarbons. A hydrocarbon composition is recovered which mainly contains hydrocarbons which are solid or semisolid at ambient temperature and pressure and an off-gas of the Fischer-Tropsch reactor, including hydrocarbons which are gaseous at ambient temperature and pressure, is used for producing hydrogen gas. By introducing hydrogen into the clean syngas, the hydrogen to carbon monoxide ratio can be increased and by using off-gas-produced hydrogen, the capacity of the process is significantly improved.Hydrogen gas is produced from the gaseous hydrocarbons of said off-gas by subjecting them to at least one reforming reaction, or to at least one shift reaction, or for example, to a combination of both. Reformer adds additional unit to the process to generate pure hydrogen.
The present invention can overcome the above mention drawbacks of prior arts. This invention focuses on producing syngas with adjustable H2/CO ratio by varying operating temperature of gasifier in the range of 600 °C to 800 °C. This invention proposes to use oxygen and steam combination as reactants to produce syngas with desired H2/CO ratio. Ratio of oxygen to coal and steam to coal will be varied to maintain required operating temperature and to achieve desired H2/CO ratio. Also the present invention aims at maximizing the gasification performance parameters like carbon conversion and efficiency of overall system by utilizing the sensible heat in syngas and subjecting unburnt carbon collected from gasification to full combustion.
OBJECTS OF THE INVENTION
An object of the present invention is to propose a process for producing syngas from fluidized bed gasification of high ash Indian coals with adjustable H2/CO ratio

Another object of present invention is to propose a process for producing syngas from fluidized bed gasification of high ash Indian coals with adjustable H2/CO ratio, in which the operating temperature of gasifier is maintained in the range of 600 °C to 800 °C with the combination of oxygen and steam as reactants.
A further object of present invention is to propose a process for producing syngas from fluidized bed gasification of high ash Indian coals with desired H2/CO ratio of 2 suitable for liquid fuels and chemicals (Methanol and Di methyl ether) production, in which the ratios of oxygen to coal and steam to coal to be varied to meet the required H2/CO ratio. Typical range of H2/CO ratio required for chemicals production varies in the range of 1 to above 2.
A still another object of the present invention is to maximize the carbon conversion and overall thermal efficiency of the complete process of fluidized bed gasification of high ash Indian coals by utilizing the sensible heat in syngas and subjecting unburnt carbon collected from gasification to full combustion.
SUMMARY OF THE INVENTION
This invention relates to a method for producing synthesis gas from fluidized bed gasification of
high ash from coal comprising:
bubbling fluidized bed gasification of coal having ash content in the range of 35% to 42% weight
forming H2 mole that CO in syngas is through accelerating steam gasification reaction and water
gas shift reaction
maintaining low gasifier operating temperature and higher steam quantity in gasification reaction
composition.

According to this invention, there is provided a process of producing syngas from fluidized bed gasification of high ash Indian coals with adjustable H2/CO ratio suitable for production of liquid fuels, synthetic fuels and chemical applications. Fluidized bed technology is more suitable to gasify high ash Indian coals to generate syngas. Air, oxygen, steam and carbon dioxide combinations are used as reactants in generating syngas from coal gasification. Syngas composition is depended on various operating parameters. Current invention relates to the process of producing syngas with adjustable H2/CO ratio,
maintaining gasifier operating temperature in the range of 600 °C to 800 °C which favors the formation reactions of more H2 than CO,
subjecting oxygen and steam as reactants,
varying oxygen to coal ratio and steam to coal ratio in order to maintain required operating temperature and to achieve required H2/CO ratio respectively,
maximizing the carbon conversion and thermal efficiency of the process by utilizing the sensible heat in syngas and subjecting unburnt carbon collected from gasification to full combustion.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In the following, present invention will be explained in more detail with reference to the
following drawings.
Fig.l schematically illustrates the Fluidized bed coal gasification process scheme with air and
steam as reactants
Fig.2 schematically illustrates the Fluidized bed coal gasification process scheme with air and
steam as reactants along with effective integration of heat from syngas.
Fig.3 schematically illustrates the Fluidized bed coal gasification process scheme with air and steam as reactants along with effective integration of heat from syngas and unburnt carbon.

DETAILED DESCRIPTION OF THE INVENTION
In figure 1, High ash Indian coal after crushing & sieving is transported through conveying system into coal feeding system consisting of hopper (1), lock vessel (2), receiver vessel (3). Coal is admitted into gasifier (11) through rotary feeder (4). Coal from coal feeding system is admitted through coal transport line into fluidized bed coal gasifier (11) at a location which is above distributor. Oxygen source (5) will be maintained with required quantity of oxygen generated from air separation unit or any other process depending upon the capacity of plant. Oxygen from oxygen source (5) is admitted into gasifier (11) in two routes, first route is through coal transport line to admit coal into gasifier (11) with settling in the pipe line and second route is through bottom of the gasifier (11) to fluidize and for partial combustion of coal inside the gasifier. Steam required for the process is generated through electric boiler (8) from water supplied through water storage tank (6) and pump (7). Steam and oxygen flow rates are maintained sufficiently to maintain the bed inventory in bubbling fluidized bed regime. Steam and oxygen are sent through electric furnace (9) to increase the medium temperature as if required for the process. Coal and fluidizing medium admitted into gasifier (11) undergoes gasification process for a provided operating conditions such as temperature, pressure, coal flow rate, oxygen & steam flow rates, bottom ash flow rates and bed inventory & residence time. Synthesis gas (Syn gas) consisting mainly of CO, C02, CH4, H2, H20 and N2 is generated through coal gasification process along with the ash & unburnt carbon formation. Coarser and fine solid particles of ash and unburnt carbon are generated in the gasifier.
Syngas composition is highly depended on process conditions maintained inside gasifier. In
general fluidized bed gasifiers are operated in the temperature ranges of 950 °C to 1050 °C below
ash fusion temperatures of high ash coals typically air being the major reactant. In the current
invention, the main interest is to generate syngas with adjustable H2/CO ratio. The favorable

conditions for more hydrogen generation in syngas are to introduce more steam as reactant and operating gasifier at lower temperatures as possible. Following are the major reactions that take place in gasification of any carbonaceous fuel,

To improve the ratio of H2/CO, formation of CO has to be reduced. Major amount of CO is formed from C02 (Boudard reaction) which is generated from combustion reaction. Primary role of combustion reaction is to supply energy required to maintain high temperature of around 1000 °C in the gasifier. In order to reduce the C02 formation indirectly CO formation, the gasifier temperature will be operated in the temperature range of 600 °C to 800 °C by limiting combustion reaction. Kinetic reaction rates of the endothermic reactions (1 & 2) also reduces due to lower temperature which causes lower formation of CO. oxygen to coal ratio range of 0.25 to 0.35 will be maintained to operate the gasifier temperature in the range of 600 °C to 800 °C.
Another way to improve H2/CO ratio is to increase H2 content in syngas. Excess quantity of steam than typical range will lead to more generation of Hydrogen. Hydrogasifictaion and water gas shift reactions will tend towards products side which is having hydrogen as one of the product due to excess amount of steam availability. Steam to coal ratio range of 0.8 to 1.2 will be maintained to achieve the desired ratio of H2/CO ratio.

Equilibrium constants of methanation reaction and water gas shift reaction are high at lower temperature i.e at 600 °C compared to that of 1000 °C. Higher equilibrium constants will favor the formation of products. Water gas shift reaction conversion will be more due to high equilibrium constant which leads to more hydrogen formation.
All the above factors will lead to increase the H2/CO ratio in the syngas composition. Lower operating temperature and higher steam quantity in the reactant will increase the H2/CO ratio to achieve desired ratio. Operating temperature of gasifier by controlling oxygen flow rate and steam flow rate into gasifier are the two critical parameters that to be varied generate the syngas with desired H2/CO ratio.
Syn gas and fine ash particles are removed from the top of the gasifier (11) and sent to gas clean up system consisting of particulates separators cyclone 1 (15), cyclone 2 (18) and candle filter (20) to remove fine ash particles in the syn gas. Heat exchanger (19) to reduce syn gas temperatures and gas cleaning system (23) consisting of absorbers to remove contaminants such as NH3, H2S & alkalis from syn gas to ensure the syn gas composition & condition meets the end use application requirement. Syngas sampling point provision to analyse syngas composition is taken after heat exchanger (19). In the scheme explained as per figure 1, the present invention is characterised by maintaining operating temperature of gasifier (11) in the range of 600 °C to 800 °C by controlling oxygen and steam flow rates in such a way to generate syngas with adjustable H2/CO ratio. Oxygen to coal ratio range of 0.25 to 0.35 and steam to coal ratio range of 0.8 to 1.2 are varied to maintain required operating conditions to achieve desired H2/CO ratio.
Carbon conversion during this process will be low due to lower operating temperature range and generation of high quantity of steam required for process will lower the overall thermal efficiency of this proposed scheme. In order to overcome the above mentioned issues, the following alternative process schemes has been proposed.
In figure 2, integration of sensible heat energy of syngas and recycling of water vapour from syngas are explained in detail. Syngas coming from gasifier (11) is sent through Gas water heat exchanger (14) to utilize the sensible heat available in syngas. Separate water line from water

storage tank (6) is sent into heat exchanger (14) to generate steam by exchanging from syngas which is at high temperature of around 600 °C to 800 °C. The flow rate of water to heat exchanger (14) is regulated such a way that it would generate the super-heated steam as much as possible. Syngas coming out of heat exchanger (14) should be above water vapor saturation level in order to avoid condensation of moisture. Steam generated from heat exchange (14) is added to the main steam line coming from electric boiler (8). The shortfall of steam required for process apart from steam generated in heat exchanger (14) is supplied by electric boiler (8). After removing fly ash from syngas, it is sent through condenser (23) and knock out drum (24) to condense the moisture in syngas and the condensate is sent to water storage tank (6) to recycle the water required for the process. This scheme utilizes the heat energy available in syngas to increase the overall thermal efficiency of the process and also recycles the required water quantity for the process to reduce water consumption.
In figure 3, integration of heat energy of syngas and energy in unburnt carbon along with ash heat is explained in detail. Solid particles after gasification consists of ash and unburnt carbon particles. Unburnt carbon particles are depended on carbon conversion achieved in the system. Carbon conversion has to maximise as possible within the gasifier by increasing the residence time. The coarser particles discharging from bottom of the gasifier and fine particles separated in cyclone 1 (15), cyclone 2 (16) and candle filter (18) are admitted into solid heat extractor (11). Oxygen from oxygen source (5) is admitted into solid heat extractor (11) from bottom to combust the unburnt particles, the total heat liberated from combustion of unburnt particles along with ash heat which will be at high temperature of around 500 °C will be exchanged with water from water storage tank (6) to extract the maximum possible energy from solid particles. Water heated from solid heat extractor (11) is sent through electric boiler (8) to further increase its temperature to match with process required condition. By utilizing energy from solid particles in the above explained manner will reduce the load on boiler and increase the overall thermal efficiency of the process.

Syngas coining from gasifier (11) is sent through Gas water heat exchanger (14) to utilize the sensible heat available in syngas. Separate water line from water storage tank (6) is sent into heat exchanger (14) to generate steam by exchanging from syngas which is at high temperature of around 600 °C to 800 °C. The flow rate of water to heat exchanger (14) is regulated such a way that it would generate the super-heated steam as much as possible. Syngas coming out of heat exchanger (14) should be above water vapor saturation level in order to avoid condensation of moisture. Steam generated from heat exchange (14) is added to the main steam line coming from electric boiler (8). The shortfall of steam required for process apart from steam generated in heat exchanger (14) is supplied by electric boiler (8). The shortfall of water quantity is sent through solid heat extractor (11) to extract the maximum possible energy from solid particles before admitting into electric boiler (8). After removing fly ash from syngas, it is sent through condenser (23) and knock out drum (24) to condense the moisture in syngas and the condensate is sent to water storage tank (6) to recycle the water required for the process. This scheme utilizes the heat energy available in solid particles and energy available in syngas along with recycling of water vapor from syngas will increase the overall thermal efficiency of process. This scheme will be more effective method to generate syngas with adjustable H2/CO ratio with high thermal efficiency.
Conversion of coal into synthesis gas (syngas) consisting of combustible gases like Carbon monoxide (CO), Hydrogen (H2) and Methane (CH4) along with other inert components like Carbon dioxide (C02), Nitrogen (N2) and water vapour (H20) through partial oxidation is called

as gasification. Gasification process is endothermic in nature and energy required to drive the process is attained through partial combustion of input coal. Coal along with combination of reactants (Air,Steam,Oxygen&C02) is admitted into gasifier which is operated at high temperature to generate syngas. Coal admitted along with air and steam mixture is known as air blown gasification. Coal admitted along with oxygen in combination with C02 and steam is known as oxy-blown gasification.
BHEL developed Bubbling fluidized bed gasifier for gasification of high ash Indian coals having
ash percentage in the range of 35 % to 42 % in weight. BHEL set up a gasification pilot plant of
1.2 TPD coal throughput capacity at Corporate R&D, Hyderabad and Demo plant of 168 TPD
coal throughput capacity atTrichy unit. Wide range of experiments carried out to establish
different fluidized bed gasification process.
Typical syngas composition generated from air blown gasification of high ash Indian coals is as
follows


H2/C0 ratio in syngas generated from air blown gasification is in the range of 0.7 to 0.8. Syngas from air blown gasification process is more suitable for power generation application where calorific value of syngas is the critical parameter. Nitrogen is the major inert in syngas composition. Air and steam mixture is admitted as gasification reactants. Air to coal ratio in the range of 2 to 2.2 and steam to coal ratio in the range of 0.1-0.2 is maintained. Gasifier operating temperatures are maintained in the range of 950 °C to 1025 °C. Typical syngas composition generated from oxy blown gasification of high ash Indian coals is as follows

H2/CO ratio in syngas generated from oxy blown gasification is in the range of 0.5 to 0.7. Syngas from oxy blown gasification process is more suitable for production of liquid fuels and chemical applications where syngas with nitrogen free gas is required.Oxygen, C02 and steam mixture is admitted as gasification reactants. C02to coal ratio in the range of 1.0 to 1.5, oxygen to coal ratio in the range of 0.5 to 0.6 and steam to coal ratio in the range of 0.1-0.2 is maintained. Gasifier operating temperatures are maintained in the range of 900 °Cto 950°C.

Syngas for liquid fuels and chemical production application should have H2/CO ratio above 2.0 whereas H2/CO ratio from oxy blown gasification process is in the range of 0.5 to 0.7. To meet this requirement syngas generated from oxy blown gasification has to send through water gas shift reactor to adjust H2/CO ratio. In order to avoid or reduce load on water gas shift reactor and to generate syngas with high H2/CO ratio, process modifications in oxy blown gasification were explored.
The current invention is related to oxy blown gasification of high ash Indian coals with oxygen and steam as gasification reactants to increase H2/CO ratio in syngas composition. In this process higher flow rates of steam is required to maintain bubbling fluidization velocity. The favourable condition for formation of more H2 than CO in syngas is through accelerating steam gasification reaction and water gas shift reaction. These two reactions are favoured at lower gasifier operating temperatures and higher steam quantity in gasification reactant composition. In view of these, optimized process parameters were found to generate syngas with more H2/CO ratio.

Typical syngas composition generated from oxy blown gasification of high ash Indian coals with oxygen and steam as gasification reactant mixture is as follows
Component Vol %
~CO I 20-30

C02 40-50
CH4 1^2
~H2 10-20
°N2 2^5
H20 10-25
H2/CO ratio in syngas composition generated from oxy blown gasification with oxygen and steam as gasification reactant is in the range of 1.0 to 2.5. To achieve the H2/CO ratio, gasifier operating temperature has to be operated in the range of 650 °C to 800 °C, steam to coal ratio in the range of 0.8 to 1.2 and oxygen to coal ratio in the range of 0.25 to 0.35. The oxygen quantity has to be decreased by 30 % and steam quantity has been increased by 4 to 5 times than that of oxygen and steam flow rates in oxy blown gasification process carried out with oxygen, C02 and steam mixture. The flow rates of oxygen and steam were adjusted in order to maintain required

gasifier operating temperature and to maintain sufficient fluidizing velocity. Due to high steam requirement in the process the overall thermal efficiency of process is low. To enhance the thermal efficiency of the proposed process, following 2 changes in process scheme have been envisaged.
1. Syngas coming out of gasifier will be at around 700 °C, generation of steam by extracting sensible heat in syngas through heat exchanger.
2. Bottom and fly ash generated from high ash coal gasification will be at around 400 °C, heating of boiler feed water to the possible extent by extracting sensible heat in ash material.
These changes in scheme will reduce load on boiler for steam generation and leads to improvement in overall thermal efficiency of the process.

WE CLAIM:

1. A method for producing synthesis gas from fluidized bed gasification of high ash coal
comprising:
bubbling fluidized bed gasification of coal having ash content in the range of 35% to 42%
by weight percentage
formingadjustable H2to CO molar ration in syngas through accelerating steam
gasification reaction and water gas shift reaction
maintaining low gasifier operating temperature and higher steam quantity in gasification
reaction composition.
2. The method as claimed in claim 1, wherein the composition of synthesis gas generated is
as follows


3. The method as claimed in claim 1, wherein H2 / CO molar ratio in syngas composition is in the range of 1.0 to 2.5
4. The process as claimed in claim 1, wherein oxygen to coal (O/C) ratio is maintained in the range of 0.25 to 0.35, steam to coal ratio (S/C) maintained in the range of 0.8 to 1.2, operating, gasifier temperature maintainedin the range of 650 °C to 800 °C to achieve H2/CO mole ratio in syngas in the range of 1.0 to 2.5
5. The process as claimed in claim 1, wherein the said process utilizes sensible heat of syngas and sensible energy in ash through heat integration of the entire scheme to render thermal efficiency.
6. The process as claimed in claim 5, wherein thesensible heat of syngas coming out of fluidized bed gasifier at 650 °C will be extracted by heat exchanger through steam generation and admitting steam into gasifier.
7. The process as claimed in claim 5, the bottom and fly ash which is at 400 °C to 500 °C is collected into heat exchanger and extraction of ash sensible heat to increase boiler feed water temperature.